Long Term Goals: The ultimate purpose of this research is to improve upon our understanding of the manner in which the self-aggregation of non-ionic amphiphiles in water and other solvent environments might influence the energetics and pathways of biochemical and biophysical processes. Specific Aims: We propose to continue to accumulate thermodynamic data for mixtures of non-ionic amphiphiles and water. There will a major focus on the enthalpies of mixing of those systems for which there is the least amount of information in the literature. We will also measure calorimetric and volumetric properties of mixtures of the same amphiphiles and the inert solvent heptane. Our recent studies give a clear indication of the formation of labile reverse micellar aggregation in the inert environment. We shall continue to develop strategies for analyzing the excess thermodynamic properties of these binary systems and for the establishment of structure-activity relationships. We plan to correlate the measured enthalpies of mixing with molecular modelling estimates of the energies of solvation of the non-ionic amphiphiles. We also wish to extend our earlier studies of the solubilization of hydrophobic metabolites by amphiphile+ water mixtures. Health Relatedness: The manner in which organic substances, including metabolites and therapeutic agents, perform in living systems is partly dictated by the nature of their functional groups and partly by their patterns of aggregation and the manner in which modify solvent structures. Our aim is to determine the effects of modifying the amphiphile's molecular structure upon the stability of the solvated clusters and the ability of such clusters to incorporate hydrophobic metabolites.